How Ford Cheated The Rules With The 2003 Ford Focus RS WRC

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“Creatively” interpreting the rules to gain an advantage over the competition has long been a tradition in motorsport, and it’s something that Ford is just as guilty of as anyone else.

Take, for instance, Ford’s car from the 2003 FIA World Rally Championship. Through a knowledgeable automotive tuner and journalist named Stav from the UK (Facebook page), we learned that the 2003 Ford Focus RS WRC used an ingenious, mostly-hidden system to store excess pressurized air from the turbocharger in a titanium tank until it could be advantageously crammed into the engine on straight portions of the course, elevating power beyond what would otherwise have been possible.

The pneumatic tank, which displaced 45 liters and was made from 2-mm-thick titanium, was situated at the back of the car, hidden by a sizable rear bumper. A 30-mm-wide titanium pipe with an electronic butterfly valve ran between it and the intake manifold, downstream from the 34-mm restrictor plate that all WRC cars were required to run at the time. That restrictor kept the engine from ever seeing its true power potential – under normal circumstances.

See, during part- and off-throttle driving, excess boost was funneled into the Ford Focus WRC’s tank by the butterfly valve. Later, when the driver pushed the throttle to the floor, the valve would let that stored pressurized air loose, providing a momentary surge of fresh air greater than what could be achieved with the restrictor plate in the way. Since the stored air had passed through the restrictor the first time around, on its way to accumulating in the tank, the system technically abided by the rule that said that all intake air must pass through the restrictor.

Strictly speaking, it was “legal.”

It took only three rally events before the Ford Focus RS WRC 03’s “surge tank” system was banned, although it’d never quite managed to be the ace in the hole that Ford had hoped for, anyway. Still, we think its a brilliant – albeit inelegant – workaround to the restrictor plate problem. Bravo, Ford.

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— Aaron Brzozowski

Aaron Brzozowski is a writer and motoring enthusiast from Detroit with an affinity for '80s German steel. He is not active on the Twitter these days, but you may send him a courier pigeon.